It's probably apartment locators posting ads. They don't have to have the listings. Any locator can take photos of any apartments and advertise them. It happens A LOT. And frequently the info doesn't get updated or removed once it is no longer available, so it just stays there, adding to the list of other people posting for that development. You could be looking at something on these sites that are over a year old and were just never removed. Also, I'm not sure what the specific situation is for Villas on Sixth, but sometime apartment complex owners start to convert and sale the units off as condos, in which case they may actually have some listing agents making the ads. It doesn't happen often but it does happen. Two examples of that is 2020 Congress and the other is Monte Vista. It's called a condo conversion. Are you looking for an apartment or condo? I can send you a free listing with more accurate info. Remember, a lot of popular sites (Zillow, CL, Trulia) don't have current info. I've seen it over a year old! That's why even though looking yourself seems like a good idea but it sure can be time consuming. Using an agent is usually a free service to you and it helps you get better data and not waste time. Let me know if I can help you. I can just email current properties and apartments if you'd like.
Hope this helps you Monika!
Email me if you want some free help.